Understanding Susceptibility of Additively Manufactured Materials to Degradation

Southwest Research Institute together with The University of Texas at San Antonio is working to gain insights into the vulnerability of additively manufactured materials to hydrogen embrittlement, a general issue that can result in mechanical hardware breaking down and losing functionality.

A $125,000 grant offered by the Connecting through Research Partnerships (Connect) Program supports the project, headed by W. Fassett Hickey of SwRI’s Mechanical Engineering Division and Brendy Rincon Troconis of UTSA’s College of Engineering.

Additive Manufacturing (AM) is a very well-known technique of producing carefully designed metallic parts via 3D printing. Although the applications of the technique are almost infinite, Hickey and Troconis specifically have an interest in additively manufactured material performance for the oil and gas and aerospace industries.

Hydrogen sulfide (H2S) is a gas that usually emerges during the drilling of oil and natural gas. The atomic hydrogen in H2S is released and is absorbed into the pipeline material and down-hole tools, which results in the deterioration of material performance. This is also referred to as hydrogen embrittlement.

In 2014, Kazakhstan’s biggest oil field was closed for two years for repairs due to hydrogen embrittlement, which led to huge cracks in its pipelines.

Atomic hydrogen is an unintended alloying element that can wreak havoc on even the most advanced and modern alloy systems.

W. Fassett Hickey, Mechanical Engineering Division, SwRI

The project will mainly concentrate on an effort to gain insights into the mechanisms of hydrogen embrittlement in additively manufactured nickel-based alloy 718, so that AM parts with less susceptibility or that are even resistant to these dangers can be designed in the future.

In order to perform this, Hickey and Troconis will explore hydrogen embrittlement on a molecular level to observe how the location of the hydrogen atoms has an impact on the integrity of the metal material under the high pressures and increased temperatures that are characteristic to drilling environments.

This will be achieved in SwRI’s unique testing facilities, which enable mechanical testing in gaseous hydrogen up to 500 °F and 3,000 PSI. The scanning Kelvin probe force microscope and thermal desorption spectrometer available from UTSA will be employed to further understand the hydrogen-alloy interaction and spatially resolve where the hydrogen is located within the alloy microstructure.

Additive manufacturing brings a lot of exciting new possibilities. We’re working with new designs that weren’t possible with traditional machining and fabrication methods.

W. Fassett Hickey, Mechanical Engineering Division, SwRI

Hickey continued, “If we can better understand the underlying mechanisms of hydrogen embrittlement in AM materials, the AM fabrication parameters and post-processing parameters of the AM parts can be designed to prevent hydrogen embrittlement, then ultimately the possibilities and applications for these AM materials are even greater.”

The Connecting through Research Partnerships Program sponsored by the Office of the Vice President for Research, Economic Development, and Knowledge Enterprise at UTSA and the Executive Office at SwRI is a grant opportunity provided to improve greater scientific partnership between the two institutions and to increase both UTSA’s and SwRI’s research-funding base with cross-campus collaborative programs.

Source: https://www.swri.org/

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